4
Refrigerant Line Connections
IMPORTANT
To avoid overheating the service valve, TXV valve, or filter
drier while brazing, wrap the component with a wet rag, or
use a thermal heat trap compound. Be sure to follow the
manufacturer’s instruction when using the heat trap
compound. Note: Remove Schrader valves from service
valves before brazing tubes to the valves. Use a brazing
alloy of 2% minimum silver content. Do not use flux.
Torch heat required to braze tubes of various sizes is
proportional to the size of the tube. Tubes of smaller size
require less heat to bring the tube to brazing temperature
before adding brazing alloy. Applying too much heat to
any tube can melt the tube. Service personnel must use
the appropriate heat level for the size of the tube being
brazed. Note: The use of a heat shield when brazing is
recommended to avoid burning the serial plate or the finish
on the unit.
1. The ends of the refrigerant lines must be cut square, de-
burred, cleaned, and be round and free from nicks or dents.
Any other condition increases the chance of a refrigerant
leak.
2. “Sweep” the refrigerant line with nitrogen or inert gas dur-
ing brazing to prevent the formation of copper-oxide in-
side the refrigerant lines. The POE oils used in R-410A
applications will clean any copper-oxide present from the
inside of the refrigerant lines and spread it throughout the
system. This may cause a blockage or failure of the me-
tering device.
3. After brazing, quench the joints with water or a wet cloth
to prevent overheating of the service valve.
4. Ensure the filter drier paint finish is intact after brazing. If
the paint of the steel filter drier has been burned or chipped,
repaint or treat with a rust preventative. This is especially
important on suction line filter driers which are continu-
ally wet when the unit is operating.
NOTE:
Be careful not to kink or dent refrigerant lines. Kinked
or dented lines will cause poor performance or compressor
damage.
Do NOT make final refrigerant line connection until plugs are
removed from refrigerant tubing.
NOTE:
Before brazing, verify indoor piston size by checking
the piston kit chart packaged with indoor unit.
Leak Testing (Nitrogen or Nitrogen-Traced)
To avoid the risk of fire or explosion, never use
oxygen, high pressure air or flammable gases for leak
testing of a refrigeration system.
WARNING
To avoid possible explosion, the line from the
nitrogen cylinder must include a pressure regulator
and a pressure relief valve. The pressure relief valve
must be set to open at no more than 150 psig.
WARNING
Pressure test the system using dry nitrogen and soapy water
to locate leaks. If you wish to use a leak detector, charge the
system to 10 psi using the appropriate refrigerant then use
nitrogen to finish charging the system to working pressure then
apply the detector to suspect areas. If leaks are found, repair
them. After repair, repeat the pressure test. If no leaks exist,
proceed to system evacuation.
System Evacuation
Condensing unit liquid and suction valves are closed to contain
the charge within the unit. The unit is shipped with the valve
stems closed and caps installed.
Do not open valves until
the system is evacuated.
REFRIGERANT UNDER PRESSURE!
Failure to follow proper procedures may cause
property damage, personal injury or death.
NOTE:
Scroll compressors should never be used to evacuate
or pump down a heat pump or air conditioning system.
Prolonged operation at suction pressures less than 20
psig for more than 5 seconds will result in overheating of
the scrolls and permanent damage to the scroll tips, drive
bearings and internal seal.
CAUTION
1. Connect the vacuum pump with 250 micron capability to
the service valves.
2. Evacuate the system to 250 microns or less using suc-
tion
and
liquid service valves. Using both valves is nec-
essary as some compressors create a mechanical seal
separating the sides of the system.
3. Close pump valve and hold vacuum for 10 minutes. Typi-
cally pressure will rise during this period.
